Platelet aggregation inhibitors

ABSTRACT

Peptides useful in inhibiting platelet aggregation are disclosed. These peptides contain the binding sequence Har-G-D and are disulfide-bridged cyclic compounds.

This application is a continuation of U.S. Ser. No. 07/806,558, filedDec. 13, 1991, now abandoned, which is a continuation-in-part of Ser.No. 07/586,610, filed Sep. 24, 1990 now abandoned, which is acontinuation-in-part of Ser. No. 07/542,488, filed Jun. 22, 1990, nowabandoned, which is a continuation-in-part of Ser. No. 07/483,229, nowU.S. Pat. No. 5,318,899, which is a continuation-in-part of Ser. No.07/418,028, filed Oct. 6, 1989, now abandoned, which is acontinuation-in-part of 07/367,509, filed Jun. 16, 1989, now abandoned.

TECHNICAL FIELD

This invention relates to a group of peptides which are, or are relatedto, platelet aggregation inhibitors isolated and purified from varioussnake venoms. These peptides are useful as therapeutic agents for thetreatment of, and prevention of, platelet-associated ischemic disorders.More specifically, the invention concerns peptides which block specificreceptors for adhesive proteins involved in platelet adherence andaggregation.

BACKGROUND ART

Heart disease is the primary cause of death in most western societies.Death from heart disease is often induced by platelet-dependent ischemicsyndromes which are initiated by atherosclerosis and arteriosclerosisand include, but are not limited to, acute myocardial infarction,chronic unstable angina, transient ischemic attacks and strokes,peripheral vascular disease, arterial thrombosis, preeclampsia,embolism, restenosis and/or thrombosis following angioplasty, carotidendarterectomy, anastomosis of vascular grafts, and chroniccardiovascular devices (e.g., in-dwelling catheters or shunts"extracorporeal circulating devices"). These syndromes represent avariety of stenotic and occlusive vascular disorders thought to beinitiated by platelet activation either on vessel walls or within thelumen by blood-borne mediators but are manifested by platelet aggregateswhich form thrombi that restrict blood flow.

Platelet aggregation is mediated by GP IIb-IIIa complex on the plateletmembrane surface. GP IIb-IIIa exists on the surface of unstimulatedplatelets in an inactive form. When platelets are activated by adhesionand the physiological agonists, the GP IIb-IIIa also becomes activatedsuch that it becomes a receptor for fibrinogen (Fg), von WillebrandFactor (vWF), and fibronectin (Fn) (see Phillips et al., Blood (1988)71:831-843); however, it is the binding of fibrinogen and/ or vonWillebrand factor that is believed to be principally responsible forplatelet aggregation and thrombus formation in vivo. Therefore,substances which specifically inhibit the binding of fibrinogen or vonWillebrand factor to GP IIb-IIIa inhibit platelet aggregation and couldbe candidates for inhibiting thrombus formation in vivo.

Several classes of peptides have been disclosed which block the bindingof adhesive proteins to activated platelets and inhibit plateletaggregation. A summary of some of this art is published in W090/15620,published 27 December 1990. This published application also discloses agroup of cyclic peptides which inhibit platelet aggregation selectively,and which are characterized by the adhesive sequence K*-G/Sar-D, whereinK* is a substituted or unsubstituted lysyl residue. The presentinvention provides additional members of this class.

DISCLOSURE OF THE INVENTION

The invention relates to members of a group of platelet aggregationinhibitors which are of the formula: ##STR1## wherein K* is asubstituted or unsubstituted lysyl residue of the formula R¹ ₂ N(CH₂)₄CHNHCO-- as described above,

wherein each R¹ is independently H, alkyl (1-6C), or at most one R¹ isR² --C═NR³,

wherein R² is H, alkyl(1-6C) or is a substituted or unsubstituted phenylor benzyl residue, or is NR⁴ ₂ in which each R⁴ is independently H oralkyl(1-6C), and

R³ is H, alkyl(1-6C), phenyl or benzyl, or

R² --C═NR³ is a radical selected from the group consisting of: ##STR2##where m is an integer of 2-3, and each R⁵ is independently H oralkyl(1-6C);

and wherein one or two (CH₂) may be replaced by O or S provided said Oor S is not adjacent to another heteroatom;

AA₁ is a small, neutral (polar or nonpolar) amino acid and n1 is aninteger of 0-3;

AA₂ is a neutral, nonpolar large (aromatic or nonaromatic) or a polararomatic amino acid and n2 is an integer of 0-3;

AA₃ is a proline residue or a modified proline residue (as definedbelow) and n3 is an integer of 0-1;

AA₄ is a neutral, small amino acid or the N-alkylated form thereof andn4 is an integer of 0-3;

each of X₁ and X₂ is independently a residue capable of forming a bondbetween X₁ and X₂ to obtain a cyclic compound as shown; and

each of Y₁ and Y₂ is independently a noninterfering substituent or maybe absent;

wherein one or more peptide linkages may optionally be replaced by alinkage selected from the group consisting of --CH₂ NH--, --CH₂ S--, CH₂CH₂ --, --CH═CH-- (cis and trans), --COCH₂ --, --CH(OH)CH₂ -- and --CH₂SO--;

with the proviso that if n3 is 0; either:

1) the sum of n2 and n4 must be at least 2; or

2) K* must be other than Hat or K; or

3) X₂ must be other than cys (C), penicillamine (Pen), or

2-amino-3,3-cyclopentanemethylene-3-mercaptopropionic acid (APmp); or

4) Y₁ or Y₂ must comprise at least one amino acid residue; or

5) one or more peptide linkages is replaced by said alternate linkage.

This invention concerns, specifically, compounds of the formula:

PAI 80 (SEQ ID NO:1) Mpr-P-Har-G-D-W-P-C-NH₂

PAI 81 (SEQ ID NO:2)Mpr-G-Har-G-D-W-P-C-NH₂

PAI 82 (SEQ ID NO:3) Mpr-A-Har-G-D-W-P-C-NH₂

PAI 83 (SEQ ID NO:4) Mpr-Aib-Har-G-D-W-P-C-NH₂

PAI 84 (SEQ ID NO:5) Mpr-(N-Me-Arg)-Har-G-D-W-P-C-NH₂

PAI 85 (SEQ ID NO:6) Mpr-(N-Me-Ser)-Har-G-D-W-P-C-NH₂

PAI 86 (SEQ ID NO:7) Mpr-D-alanine-Har-G-D-W-P-C-NH₂

PAI 87 (SEQ ID NO:8) Mpr-(β-Ala)-Har-G-D-W-P-C-NH ₂

PAI 88 (SEQ ID NO:9) Mpr-(N-Me-Leu)-Har-G-D-W-P-C-NH₂

PAI 89 (SEQ ID NO:10) Mpr-(N-Me-Ala)-Har-G-D-W-P-C-NH₂

PAI 90 (SEQ ID NO:11) Mpr-Sar-Har-G-D-W-P-C-NH₂

PAI 91 (SEQ ID NO:12) Mpr-V-Har-G-D-W-P-C-NH₂

PAI 92 (SEQ ID NO:13) Mpr-S-Har-G-D-W-P-C-NH₂

PAI 93 (SEQ ID NO:14) Mpr-Har-G-D-W-P-A-C-NH₂

PAI 94 (SEQ ID NO:15) Mpr-Har-G-D-W-P-(N-Me-Ala)-C-NH₂

PAI 95 (SEQ ID NO:16) Mpr-Har-G-D-W-P-G-C-NH₂

PAI 96 (SEQ ID NO:17) Mpr-Har-G-D-W-P-At-C-NH₂

PAI 97 (SEQ ID NO:18) Mpr-Har-G-D-W-P-P-C-NH₂

PAI 98 (SEQ ID NO:19) Mpr-Har-G-D-W-P-(Sar)-C-NH₂

PAI 99 (SEQ ID NO:20) Mpr-Har-G-D-W-P-(Aib)cys-NH₂

PAI 100 (SEQ ID NO:21) Mpr-A-(Har)-G-D-W-P-Pen-NH₂

PAI 101 (SEQ ID NO:22) Mpr-A-K-G-D-W-P-Pen-NH₂

PAI 102 (SEQ ID NO:23) Mpr-D-(Har)-G-D-W-P-Pen-NH₂

The invention also concerns pharmaceutical compositions containing thepeptides of the invention and methods to inhibit platelet aggregationusing these peptides and formulations.

MODES OF CARRYING OUT THE INVENTION

The invention peptides can be synthesized and tested according to themethods described in W090/15620, published Dec. 27, 1990 andincorporated herein by reference. Furthermore, antibodies may beprepared to these peptides as set forth therein. Briefly, compoundswithin the scope of the present invention can be synthesized chemicallyby means well known in the art such as, e.g., solid-phase peptidesynthesis. The synthesis is commenced from the carboxy-terminal end ofthe peptide using an alpha-amino protected amino acid.t-Butyloxycarbonyl (Boc) protective groups can be used for all aminogroups even though other protective groups such asfluorenylmethyloxycarbonyl (Fmoc), are suitable. For example,Boc-Gly-OH, Boc-Ala-OH, Boc-His (Tos)-OH, (i.e., selectedcarboxy-terminal amino acids) can be esterified to chloromethylatedpolystyrene resin supports, p-methyl benzhydrylamine (pMBHA) or PAMresins. The polystyrene resin support is preferably a copolymer ofstyrene with about 0.5 to 2% divinyl benzene as a cross-linking agentwhich causes the polystyrene polymer to be completely insoluble incertain organic solvents. See Stewart, et al., Solid-Phase PeptideSynthesis (1969) W. H. Freeman Co., San Francisco and Merrifield, J AmChem Soc (1963) 85:2149-2154. These and other methods of peptidesynthesis are also exemplified by U.S. Pat. Nos. 3,862,925, 3,842,067,3,972,859, and 4,105,602.

The synthesis may use manual synthesis techniques or automaticallyemploy, for example, an Applied BioSystems 430A or 431A PeptideSynthesizer (Foster City, Calif.) following the instructions provided inthe instruction manual supplied by the manufacturer. Cleavage of thepeptides from the resin can be performed using the "low-high" HFdeprotection protocols as described in Lu, G.-S., et al., Int J Peptide& Protein Res (1987) 29:545-557. Refolding of analogs of the snake venomPAIs can be performed using the procedure outlined in Garsky, V., etal., Proc Natl Acad Sci USA (1989) 86:4022-4026 which describes thesolid-phase synthesis of echistatin.

It will be readily appreciated by those having ordinary skill in the artof peptide synthesis that the intermediates which are constructed inaccordance with the present disclosure during the course of synthesizingthe present analog compounds are themselves novel and useful compoundsand are thus within the scope of the invention.

Alternatively, selected compounds of the present invention can beproduced by expression of recombinant DNA constructs prepared inaccordance with well-known methods. Such production can be desirable toprovide large quantities or alternative embodiments of such compounds.Since the peptide sequences are relatively short, recombinant productionis facilitated; however, production by recombinant means is particularlypreferred over standard solid phase peptide synthesis for peptides of atleast 8 amino acid residues.

Antibodies

Antibodies to the compounds of the invention may be prepared by standardimmunization protocols involving administering these compounds tovarious vertebrates, such as rabbits, rats, mice, sheep, and chickensresult in antisera which are immunoreactive with the purified peptide.The compounds of the invention may be advantageously conjugated to asuitable antigenically neutral carrier, such as an appropriate serumalbumin or keyhole limpet hemocyanin, in order to enhanceimmunogenicity. In addition, the free peptide can be injected withmethylated BSA as an alternative to conjugation. Furthermore, theantibody-secreting cells of the immunized mammal can be immortalized togenerate monoclonal antibody panels which can then be screened forreactivity with the peptides.

The resulting polyclonal or monoclonal antibody preparations are usefulin assays for levels of the corresponding peptides in biological samplesusing standard immunoassay procedures.

Assays

The compounds of the invention are tested for platelet aggregationinhibition (PAI) activity using an assay performed as follows. GPIIb-IIIa, prepared in purified form, for example as described byFitzgerald, L. A., et al., Anal Biochem (1985) 151:169-177, incorporatedherein by reference, is coated onto a solid support such as beads, testtubes, or microtiter plates. The coated support is then contacted withfibrinogen and with the test material and incubated for a sufficienttime to permit maximal binding of fibrinogen to the immobilized GPIIb-IIIa. Fibrinogen is typically provided at a concentration of about5-50 nM and the test material can, if desired, be added at a series ofdilutions. Typical incubations are 2-4 hr at 35° C., the time andtemperature being interdependent.

After incubation, the solution containing the fibrinogen and testmaterial is removed and the level of binding of fibrinogen measured byquantitating bound fibrinogen to GP IIb-IIIa. Any suitable means ofdetection may be used, but it is convenient to employ labeledfibrinogen, for example using radioactive, fluorescent or biotinylatedlabels. Such methods are well known and need not be elaborated here.

Assessment of the results is aided by employing a control sample,usually identical to the test sample except that the test substance isabsent. In this case, percent inhibition may be calculated using theamount of Fg bound in the control as representing the basis, so that##EQU1##

Other measures of inhibition effectiveness, such as IC₅₀, may also beused.

The assay systems of the invention further include characterization ofthe PAI specificity by binding inhibition assays identical to that abovebut substituting other adhesive proteins for Fg and other receptors forGP IIb-IIIa. In particular, inhibition of the binding of vitronectin tothe vitronectin receptor; fibronectin to the fibronectin receptor;fibronectin to GP IIb-IIIa and fibrinogen and/or vWF to GP IIb-IIIa maybe assessed. The adhesive protein and receptors for these assays areavailable in the art.

In addition to the plate assays of the invention, other assays forplatelet aggregation inhibition activity and related activities are alsoavailable, as set forth above. In summary, a list of commonly employedassays is as follows:

1. The plate assays utilizing specific receptors described in theprevious paragraphs;

2. Standard assays directly applied to platelet aggregation, such asthose described by Gann, Z.-R., et al., J Biol Chem (1988)263:19827-19832; Huang, T. F., et al., J Biol Chem (1987)262:16157-16163; Biochemistry (1989) 28:661-666, cited above andincorporated herein by reference;

3. An in vivo thrombosis model in dogs as described hereinbelow inExample 1, and by Folts, J. D., et al., Circulation (1976) 54:365; and

4. Effect on cell adhesion using S35 methionine-labeled cells asdescribed hereinbelow in Example 19.

Administration and Utility

The PAIs of the invention are useful therapeutically to prevent thrombusformation. Indications appropriate to such treatment include, withoutlimitation, atherosclerosis and arteriosclerosis, acute myocardialinfarction, chronic unstable angina, transient ischemic attacks andstrokes, peripheral vascular disease, arterial thrombosis, preeclampsia,embolism, restenosis and/or thrombosis following angioplasty, carotidendarterectomy, anastomosis of vascular grafts, and chroniccardiovascular devices (e.g., in-dwelling catheters or shunts"extracorporeal circulating devices"). These syndromes represent avariety of stenotic and occlusive vascular disorders thought to beinitiated by platelet activation on vessel walls.

The PAIs may be used for prevention or abortion of arterial thrombusformation, in unstable angina and arterial emboli or thrombosis, as wellas treatment or prevention of myocardial infarction (MI) and muralthrombus formation post MI. For brain-related disorders, treatment orprevention of transient ischemic attack and treatment of thromboticstroke or stroke-in-evolution are included.

The PAIs may also be used for prevention of platelet aggregation,embolization, or consumption in extracorporeal circulations, includingimproving renal dialysis, cardiopulmonary bypasses, hemoperfusions, andplasmapheresis.

PAIs prevent platelet aggregation, embolization, or consumptionassociated with intravascular devices, and administration results inimproved utility of intraaortic balloon pumps, ventricular assistdevices, and arterial catheters.

The PAIs will also be useful in treatment or prevention of venousthrombosis as in deep venous thrombosis, IVC, renal vein or portal veinthrombosis, and pulmonary venous thrombosis.

Various disorders involving platelet consumption, such as thromboticthrombocytopenic purpura are also treatable.

In addition, the PAIs of the present invention may be used in numerousnontherapeutic applications where inhibiting platelet aggregation isdesired. For example, improved platelet and whole blood storage can beobtained by adding sufficient quantities of the peptides, the amount ofwhich will vary depending upon the length of proposed storage time, theconditions of storage, the ultimate use of the stored material, etc.

The PAI dosage can range broadly depending upon the desired affects andthe therapeutic setting. Typically, dosages will be between about 0.01and 10 mg/kg, preferably between about 0.01 to 0.1 mg/kg, body weight.Administration is preferably parenteral, such as intravenous on a dailybasis for up to a week or as much as one or two months or more, all ofwhich will vary with the peptide's size. If the peptides aresufficiently small (e.g., less than about 8-10 amino acid residues)other routes of administration can be utilized, such as intranasally,sublingually, or the like.

Injectables can be prepared in conventional forms, either as liquidsolutions or suspensions, solid forms suitable for solution orsuspension in liquid prior to injection, or as emulsions. Suitableexcipients are, for example, water, saline, dextrose, mannitol, lactose,lecithin, albumin, sodium glutamate, cysteine hydrochloride or the like.In addition, if desired, the injectable pharmaceutical compositions maycontain minor amounts of nontoxic auxiliary substances, such as wettingagents, pH buffering agents, and the like. If desired, absorptionenhancing preparations (e.g., liposomes) may be utilized.

Preparation A Preparation of G-C-G-K-G-D-W-P-C-A-NH₂

One-half mmol of pMBHA resin (0.72 meq/g, Applied Biosystems,Foster/City, Calif.) was subjected to Procedure A with the requiredamino acids (introduced in order). The Boc-protected amino acids had thefollowing side-chain protection: Asp(O-cHex), Cys(4-MeBzl), andLys(Cl-Z). Following completion of the assembly of the protectedpeptide-resin, the amino terminal Boc group was removed with TFA and theresin dried as its TFA-salt form. The resin (1.54 g) was treated withanhydrous hydrogen fluoride (HF) containing 10% anisole, 2% ethyl methylsulfide for 30 min at -10° C., and an additional 30 min at 0° C. The HFwas removed in vacuo and the peptide/resin mixture was suspended indiethyl ether followed by alternately washing with chloroform and ether3X. After a final ether wash, the peptide was extracted from the resinwith 2.0M acetic acid, diluted with distilled water and lyophilized.

The crude peptide (370 mg) was dissolved in deoxygenated 10 mM NH₄ OAc,pH 8, to 0.5 mg/ml and allowed to oxidize by dropwise addition of aslight excess of 0.01M potassium ferricyanide (K₃ Fe(CN)₆) solution,stirred an additional 20 min, and adjusted to pH 5 with acetic acid. Thepeptide solution was treated with DOWEX AG3x4 anion-exchange resin for15 min with stirring and the resin filtered, diluted with H₂ O andlyophilized to yield the crude cyclized peptide. The crude cyclizedpeptide (392 mg) was purified by desalting on Sephadex G-25F using 0.5Macetic acid as eluent, followed by ion-exchange chromatography onCM-Sepharose (Pharmacia) using an elution gradient generated by additionof 100 mM NH₄ OAc to a solution of 10 mM NH₄ OAc, pH 4.5. Fractionswhich had a minimum purity of 90% by HPLC analysis were pooled andlyophilized from H₂ O several time to yield 175 mg. Final purificationconsisted of preparative HPLC purification on a Water C-18 reverse-phasecolumn with an acetonitrile/water/TFA gradient to yield purifiedpeptide.

EXAMPLE 1 Preparation of Additional Analogs

The following analogs were synthesized in a manner similar to that setforth in Preparation A and were tested for PAI activity in the assaymethod described hereinabove.

    __________________________________________________________________________                                        Appr. IC.sub.50                           Analog      Sequence                (μM)                                   __________________________________________________________________________    PAI 80 (SEQ ID NO:1)                                                                      Mpr--P--Har--G--D--W--P--C--NH.sub.2                                                                  1.29                                      PAI 81 (SEQ ID NO:2)                                                                      Mpr--G--Har--G--D--W--P--C--NH.sub.2                                                                  7.47                                      PAI 82 (SEQ ID NO:3)                                                                      Mpr--A--Har--G--D--W--P--C--NH.sub.2                                                                  0.12                                      PAI 83 (SEQ ID NO:4)                                                                      Mpr--Aib--Har--G--D--W--P--C--NH.sub.2                                                                2.20                                      PAI 84 (SEQ ID NO:5)                                                                      Mpr--(N--Me--Arg)--Har--G--D--W--P--C--NH.sub.2                                                       0.25                                      PAI 85 (SEQ ID NO:6)                                                                      Mpr--(N--Me--Ser)--Har--G--D--W--P--C--NH.sub.2                                                       0.28                                      PAI 86 (SEQ ID NO:7)                                                                      Mpr--D-alanine-Har--G--D--W--P--C--NH.sub.2                                                           1.15                                      PAI 87 (SEQ ID NO:8)                                                                      Mpr--(β-Ala)-Har--G--D--W--P--C--NH.sub.2                                                        0.92                                      PAI 88 (SEQ ID NO:9)                                                                      Mpr--(N--Me--Leu)--Har--G--D--W--P--C--NH.sub.2                                                       0.84                                      PAI 89 (SEQ ID NO:10)                                                                     Mpr--(N--Me--Ala)--Har--G--D--W--P--C--NH.sub.2                                                       0.62                                      PAI 90 (SEQ ID NO:11)                                                                     Mpr--Sar--Har--G--D--W--P--C--NH.sub.2                                                                0.27                                      PAI 91 (SEQ ID NO:12)                                                                     Mpr--V--Har--G--D--W--P--C--NH.sub.2                                                                  0.35                                      PAI 92 (SEQ ID NO:13)                                                                     Mpr--S--Har--G--D--W--P--C--NH.sub.2                                                                  0.24                                      PAI 93 (SEQ ID NO:14)                                                                     Mpr--Har--G--D--W--P--A--C--NH.sub.2                                                                  3.33                                      PAI 94 (SEQ ID NO:15)                                                                     Mpr--Har--G--D--W--P--(N--Me--Ala)--C--NH.sub.2                                                       1.46                                      PAI 95 (SEQ ID NO:16)                                                                     Mpr--Har--G--D--W--P--G--C--NH.sub.2                                                                  8.66                                      PAI 96 (SEQ ID NO:17)                                                                     Mpr--Har--G--D--W--P--A.sup.† --C--NH.sub.2                                                    0.23                                      PAI 97 (SEQ ID NO:18)                                                                     Mpr--Har--G--D--W--P--P--C--NH.sub.2                                                                  1.40                                      PAI 98 (SEQ ID NO:19)                                                                     Mpr--Har--G--D--W--P--(Sar)--C--NH.sub.2                                                              0.31                                      PAI 99 (SEQ ID NO:20)                                                                     Mpr--Har--G--D--W--P--(Aib)Cys--NH.sub.2                                                              0.46                                      PAI 100 (SEQ ID NO:21)                                                                    Mpr--A--(Har)--G--D--W--P--Pen--NH.sub.2                                                              0.37                                      PAI 101 (SEQ ID NO:22)                                                                    Mpr--A--K--G--D--W--P--Pen--NH.sub.2                                                                  4.91                                      PAI 102 (SEQ ID NO:23)                                                                    Mpr--D--(Har)--G--D--W--P--Pen--NH.sub.2                                                              4.04                                      __________________________________________________________________________

    __________________________________________________________________________    SEQUENCE LISTING                                                              (1) GENERAL INFORMATION:                                                      (iii) NUMBER OF SEQUENCES: 23                                                 (2) INFORMATION FOR SEQ ID NO:1:                                              (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 3                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:1:                                       XaaProXaaGlyAspTrpProCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:2:                                              (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 3                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2:                                       XaaGlyXaaGlyAspTrpProCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:3:                                              (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 3                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3:                                       XaaAlaXaaGlyAspTrpProCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:4:                                              (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 2                                                               (D) OTHER INFORMATION: /note= "Should be Aib"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 3                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:4:                                       XaaXaaXaaGlyAspTrpProCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:5:                                              (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 2                                                               (D) OTHER INFORMATION: /note= "Should be N-Me-Arg"                            (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 3                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:5:                                       XaaXaaXaaGlyAspTrpProCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:6:                                              (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 2                                                               (D) OTHER INFORMATION: /note= "Should be N-Me-Ser"                            (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 3                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:6:                                       XaaXaaXaaGlyAspTrpProCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:7:                                              (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 3                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 2                                                               (D) OTHER INFORMATION: /note= "Should be D-Ala"                               (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:7:                                       XaaXaaXaaGlyAspTrpProCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:8:                                              (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 2                                                               (D) OTHER INFORMATION: /note= "Should be bAla"                                (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 3                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:8:                                       XaaXaaXaaGlyAspTrpProCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:9:                                              (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 2                                                               (D) OTHER INFORMATION: /note= "Should be N-Me-Leu"                            (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 3                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:9:                                       XaaXaaXaaGlyAspTrpProCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:10:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 2                                                               (D) OTHER INFORMATION: /note= "Should be N-Me-Ala"                            (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 3                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:10:                                      XaaXaaXaaGlyAspTrpProCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:11:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 2                                                               (D) OTHER INFORMATION: /note= "Should be Sar"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 3                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:11:                                      XaaXaaXaaGlyAspTrpProCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:12:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 3                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:12:                                      XaaValXaaGlyAspTrpProCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:13:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 3                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:13:                                      XaaSerXaaGlyAspTrpProCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:14:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear,                                                         (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 2                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:14:                                      XaaXaaGlyAspTrpProAlaCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:15:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 2                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 7                                                               (C) OTHER INFORMATION: /note= "Should be N-Me-Ala"                            (xi) SEQUENCE DESCRIPTION: SEQ ID NO:15:                                      XaaXaaGlyAspTrpProXaaCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:16:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 2                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:16:                                      XaaXaaGlyAspTrpProGlyCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:17:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 2                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 7                                                               (c) OTHER INFORMATION: /note= "Should be D-Ala"                               (xi) SEQUENCE DESCRIPTION: SEQ ID NO:17:                                      XaaXaaGlyAspTrpProXaaCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:18:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 2                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:18:                                      XaaXaaGlyAspTrpProProCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:19:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 2                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 7                                                               (D) OTHER INFORMATION: /note= "Should be Sar"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:19:                                      XaaXaaGlyAspTrpProXaaCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:20:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 2                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 7                                                               (D) OTHER INFORMATION: /note= "Should be Aib"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:20:                                      XaaXaaGlyAspTrpProXaaCys                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:21:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 3                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 8                                                               (D) OTHER INFORMATION: /note= "Should be Pen"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:21:                                      XaaAlaXaaGlyAspTrpProXaa                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:22:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 8                                                               (D) OTHER INFORMATION: /note= "Should be Pen"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:22:                                      XaaAlaLysGlyAspTrpProXaa                                                      15                                                                            (2) INFORMATION FOR SEQ ID NO:23:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 8 amino acids                                                     (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 1                                                               (D) OTHER INFORMATION: /note= "Should be Mpr"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 3                                                               (D) OTHER INFORMATION: /note= "Should be Har"                                 (ix) FEATURE:                                                                 (A) NAME/KEY: Modified-site                                                   (B) LOCATION: 8                                                               (D) OTHER INFORMATION: /note= "Should be Pen"                                 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:23:                                      XaaAspXaaGlyAspTrpProXaa                                                      15                                                                            __________________________________________________________________________

I claim:
 1. A peptide selected from the group consisting of:

    ______________________________________                                        PAI 80                                                                              Mpr-P-Har-G-D-W-P-C-NH.sub.2                                                                       (SEQ ID No:1)                                      PAI 81                                                                              Mpr-G-Har-G-D-W-P-C-NH.sub.2                                                                       (SEQ ID No:2)                                      PAI 83                                                                              Mpr-Aib-Har-G-D-W-P-C-NH.sub.2                                                                     (SEQ ID No:4)                                      PAI 84                                                                              Mpr-(N-Me-Arg)-Har-G-D-W-P-C-NH.sub.2                                                              (SEQ ID No:5)                                      PAI 85                                                                              Mpr-(N-Me-Ser)-Har-G-D-W-P-C-NH.sub.2                                                              (SEQ ID No:6)                                      PAI 86                                                                              Mpr-(D-Ala)-Har-G-D-W-P-C-NH.sub.2                                                                 (SEQ ID No:7)                                      PAI 87                                                                              Mpr-(β-Ala)-Har-G-D-W-P-C-NH.sub.2                                                            (SEQ ID No:8)                                      PAI 88                                                                              Mpr-(N-Me-Leu)-Har-G-D-W-P-C-NH.sub.2                                                              (SEQ ID No:9)                                      PAI 89                                                                              Mpr-(N-Me-Ala)-Har-G-D-W-P-C-NH.sub.2                                                              (SEQ ID No:10)                                     PAI 90                                                                              Mpr-Sar-Har-G-D-W-P-C-NH.sub.2                                                                     (SEQ ID No:11)                                     PAI 91                                                                              Mpr-V-Har-G-D-W-P-C-NH.sub.2                                                                       (SEQ ID No:12)                                     PAI 93                                                                              Mpr-Har-G-D-W-P-A-C-NH.sub.2                                                                       (SEQ ID No:14)                                     PAI 94                                                                              Mpr-Har-G-D-W-P-(N-Me-Ala)-C-NH.sub.2                                                              (SEQ ID No:15)                                     PAI 95                                                                              Mpr-Har-G-D-W-P-C-NH.sub.2                                                                         (SEQ ID No:16)                                     PAI 96                                                                              Mpr-Har-G-D-W-P-(D-Ala)-C-NH.sub.2                                                                 (SEQ ID No:17)                                     PAI 97                                                                              Mpr-Har-G-D-W-P-P-C-NH.sub.2                                                                       (SEQ ID No:18)                                     PAI 98                                                                              Mpr-Har-G-D-W-P-(Sar)-C-NH.sub.2                                                                   (SEQ ID No:19)                                     PAI 99                                                                              Mpr-Har-G-D-W-P-(Aib)-C-NH.sub.2                                                                   (SEQ ID No:20)                                     PAI 100                                                                             Mpr-A-(Har)-G-D-W-P-Pen-NH.sub.2                                                                   (SEQ ID No:21)                                     PAI 101                                                                             Mpr-A-K-G-D-W-P-Pen-NH.sub.2                                                                       (SEQ ID No:22), and                                PAI 102                                                                             Mpr-D-(Har)-G-D-W-P-Pen-NH.sub.2                                                                   (SEQ ID No.23).                                    ______________________________________                                    


2. The peptide of claim 1, wherein said peptide is a cyclic peptidecomprising a bond between ( 1) a terminal Mpr and a terminal Cys or (2)a terminal Mpr and a terminal Pen.
 3. The peptide of claim 1, whereinsaid peptide is ##STR3##
 4. The peptide of claim 1, wherein said peptideis ##STR4##
 5. The peptide of claim 1, wherein said peptide is ##STR5##6. The peptide of claim 1, wherein said peptide is ##STR6##
 7. Thepeptide of claim 1, wherein said peptide is ##STR7##
 8. The peptide ofclaim 1, wherein said peptide is ##STR8##
 9. The peptide of claim 1,wherein said peptide is ##STR9##
 10. The peptide of claim 1, whereinsaid peptide is ##STR10##
 11. The peptide of claim 1, wherein saidpeptide is ##STR11##
 12. The peptide of claim 1, wherein said peptide is##STR12##
 13. The peptide of claim 1, wherein said peptide is ##STR13##14. The peptide of claim 1, wherein said peptide is ##STR14##
 15. Thepeptide of claim 1, wherein said peptide is ##STR15##
 16. The peptide ofclaim 1, wherein said peptide is ##STR16##
 17. The peptide of claim 1,wherein said peptide is ##STR17##
 18. The peptide of claim 1, whereinsaid peptide is ##STR18##
 19. The peptide of claim 1, wherein saidpeptide is ##STR19##
 20. The peptide of claim 1, wherein said peptide is##STR20##
 21. The peptide of claim 1, wherein said peptide is ##STR21##22. The peptide of claim 1, wherein said peptide is ##STR22##
 23. Thepeptide of claim 1, wherein said peptide is ##STR23##